Re: [Mip6] [issue94] fixing encapsulation mechanism in IPv4 network

[Vijay Devarapalli <vijay.devarapalli at azairenet.com>]

Hello,

Keiichi SHIMA wrote:
> New submission from Keiichi SHIMA <keiichi at iijlab.net>:
>
> The current DSMIPv6 draft specifies two encapsulation formats, one is the IPv4 encap format, the other is 
> UDPv4 encap format.  The default encapsulation format is the IPv4 format, and if the HA explicitly 
> specifies to change the encapsulation format to the UDPv4 format if there is a NAT box between the HA 
> and the MN.  Because of this specification, HA and MN have to support both encapsulation formats and 
> have to change the format dynamically, that may increase the hurdle for implementors and may cause 
> complexity in interoperability.

If I remember right, this was among the first few issues that
were discussed in the design team. Some folks did suggest
turning on UDP all the time when the access network is IPv4.
But this is an overhead in case there is no NAT. Thats why
we have a NAT detection mechanism in the DS-MIPv6. UDP
encapsulation is turned on only if a NAT is detected. My
preference is to still go with this.

> Isn't it possible to fix the encapsulation format to one of these mechanisms described in the draft?

If we are to pick only one encapsulation format, we clearly
can't pick "IPv4 encap format" (as you called it) because it
may not work through a NAT. It has to be UDP encapsulation
always.

Vijay

> ----------
> category: Technical
> draft: draft-ietf-mip6-nemo-v4traversal
> messages: 338
> nosy: keiichi
> priority: May fix
> status: No discussion
> title: fixing encapsulation mechanism in IPv4 network
>
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> <http://www.mip4.org/issues/tracker/mip6/issue94>
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